TAURIN. 95 



a liquid holding carbonate and sulphohydrate of ammonia in so- 

 lution. 



When aposepedin is heated on polished silver, the metal is 

 blackened, being converted into sulphuret. At the temperature 

 of 57 aposepedin is soluble in%2 times its weight of water. The 

 solution speedily putrefies, and acquires a very disagreeable smell. 



Aposepedin is very soluble in alcohol. When a boiling alco- 

 holic solution cools, the oxide is precipitated under the form of 

 a fine light powder, which after being dried, has a good deal of 

 resemblance to magnesia. Nitric acid converts it into a bitter 

 matter and a yellow oil ; but no oxalic acid is formed. Muria- 

 tic acid dissolves a greater quantity of it than water, and when 

 the solution is concentrated it concretes into a mass on cooling. 



The aqueous solution of aposepedin is neither precipitated by 

 alum nor persulphate of iron. The infusion of nut-galls throws 

 it down abundantly in flocks, which are redissolved by adding a 

 great excess of the reagent. When mixed with a solution of su- 

 gar no fermentation is produced. 



The portion of the cheese dissolved in ammonia owes its acid 

 properties to acetate of ammonia, generated during the putrefac- 

 tion of the cheese. It contained also a brown extractive matter, 

 ammonia-phosphate of soda and a brown oil, heavier than water, 

 and having an acrid and burning taste. Braconnot considered 

 it as a compound of oleic acid with an acrid oil. 



CHAPTER IX. 



OF TAURIN. 



THIS substance was discovered by L. Gmelin in 1824, during 

 the researches of Tiedemann and Gmelin on ox bile ; and its pro- 

 perties were described by him in 1827.* They distinguished it 

 by the name of gallenasparagin, which L. Gmelin afterwards 

 changed into taurin, obviously from the Latin name of the ani- 

 mal from whose bile it was extracted. There can be little doubt 

 that it was formed from the choleic acid of bile by the processes 

 to which Gmelin subjected ox bile ; though he was of opinion 

 that it constituted one of the many ingredients of which he con- 



* Poggendorf's Annalen, viii. 326. 



